Interpretive Summary: Wetland resource managers need accurate and timely information for management and assessment of aquatic ecosystems. Consequently, remote sensing has become an important tool for monitoring these areas. Field hyperspectral reflectance data were studied at 50 wavebands (10 nm bandwidth) over the 400 to 900 nm spectral range to determine their potential for distinguishing among nine aquatic plant species: American lotus, American pondweed, giant duckweed, Mexican waterlily, white waterlily, spatterdock, giant salvinia, waterhyacinth, and waterlettuce. The species were studied on three dates: May 30, July 1, and August 3, 2009. Two procedures were used to determine the optimum bands for discriminating among species: multiple comparison range tests and stepwise discriminant analysis. Multiple comparison range tests results for May showed that the most separations among species occurred at bands in the near-infrared (NIR) spectral region where up to six species could be distinguished. For July, few species could be distinguished. The optimum bands in August occurred in the green, red, and red-NIR edge spectral regions where up to six species could be distinguished. Stepwise discriminant analysis identified 11 bands in the blue, green, red-NIR edge and NIR regions to be significant to discriminate among the species in May. For July and August, stepwise discriminant analysis identified 15 bands and 13 bands, respectively, from the blue to NIR regions to be significant for discriminating among the species. These results provide insight for determining the optimum bands when using hyperspectral imagery captured from aircraft or satellite platforms for identifying the aquatic plant species studied here and should be useful to wetland resource managers.

Technical Abstract:
In situ hyperspectral reflectance data were studied at 50 bands (10 nm bandwidth) over the 400 to 900 nm spectral range to determine their potential for distinguishing among nine aquatic plant species: American lotus [Nelumbo lutea (Willd.) Pers.], American pondweed (Potamogeton nodusus Poir.), giant duckweed [Spirodela polyrrhiza (L.) Schleid.], Mexican waterlily (Nymphaea mexicana Zucc.), white waterlily (Nymphaea odorata Aiton), spatterdock [Nuphar lutea (L.) Sm.], giant salvinia (Salvinia molesta Mitchell), waterhyacinth [Eichhornia crassipes (Mart.) Solms], and waterlettuce (Pistia stratiotes L.). The species were studied on three dates: May 30, July 1, and August 3, 2009. All nine species were studied in July and August, while only eight species were studied in May; giant duckweed was not studied in May due to insufficient availability. Two procedures were used to determine the optimum bands for discriminating among species: multiple comparison range tests and stepwise discriminant analysis. Multiple comparison range tests results for May showed that most separations among species occurred at bands 795 to 865 nm in the NIR spectral region where up to six species could be distinguished. For July, few species could be distinguished among the 50 bands; most separations occurred at the 715 nm red-NIR edge band where four species could be differentiated. The optimum bands in August occurred in the green (525 to 595 nm), red (605 to 635 nm) and red-NIR edge (695 to 705 nm) spectral regions where up to six species could be distinguished. Stepwise discriminant analysis identified 11 bands in the blue, green, red-NIR edge, and NIR spectral regions to be significant to discriminate among the eight species in May. For July and August, stepwise discriminant analysis identified 15 bands and 13 bands, respectively, from the blue to NIR regions to be significant for discriminating among the nine species.